Effects of supplemental dietary l‐carnitine and ractopamine on the performance of juvenile rainbow trout,Oncorhynchus mykiss

This study was carried out to investigate a possible protein‐sparing action of l ‐carnitine and ractopamine in rainbow trout, Oncorhynchus mykiss. An 8‐week feeding trial was carried out to evaluate the effects of supplementation of three levels of l ‐carnitine (0, 1 and 2 g kg^?1) and two levels of ractopamine (0 and 10 mg kg^?1) on growth performance, fillet fatty acid compositions and blood biochemical parameters in a 3 × 2 factorial experimental design. Ractopamine and 1 g kg^?1 carnitine improved the specific growth rate (1.03% and 1.05% day^?1), feed conversion ratio (FCR, 1.3 and 1.29), protein efficiency ratio (PER, 1.88 and 1.85) of fish and crude protein (73.5 and 73.8) content of fish fillet. l ‐carnitine and ractopamine increased the levels of albumin, total protein and globulin in the serum of fish. Apart from eicosapentaenoic acid and docosahexaenoic acid, other fatty acids of fish fillet were increased by ractopamine, while total saturated fatty acids were almost intact. However, the total n‐3 poly unsaturated fatty acids were reduced by l ‐carnitine supplementation (P<0.05). The present study showed that 1 g kg^?1l ‐carnitine and 10 mg kg^?1 ractopamine each can improve the performance of rainbow trout and their combination in diet could enhance the protein level and change the fatty acids profile in fillet muscle.     

Larval feeding behaviour of angel fish Pterophyllum scalare (Cichlidae) fed copepod Eucyclops serrulatus and cladoceran Ceriodaphnia quadrangula

Three different live diets, Eucyclops serrulatus, Ceriodaphnia quadrangula and equal combination of E. serrulatus copepodid and C. quadrangula, were offered to angelfish (Pterophyllum scalare) larvae viz 1‐week, 2‐week and 3‐week old at prey densities of 2, 5 and 10 individuals mL^?1. Results showed that 1‐week‐old P. scalare larvae consumed E. serrulatus copepodid at a rate of 31.3–56.7 ind. h^?1, C. quadrangula at 8.0–12.0 ind. h^?1, and mixture of E. serrulatus and C. quadrangula at 20.7–40.7 ind. h^?1. For 2‐week‐ and 3‐week‐old larvae, consumption rate increased accordingly. The electivity indices (E) of P. scalare (1‐week‐old larvae) for E. serrulatus copepodid were +0.18, +0.23 and +0.22 at prey densities of 2, 5 and 10 ind. mL^?1 respectively. Tendency towards E. serrulatus copepodid consumption reduced by aging P. scalare as indicated by the E values for 2‐ and 3‐week‐old larvae. However, growth and survival of P. scalare larvae was greatest when fed on combination of copepod E. serrulatus and C. quadrangula.     

Resting Egg Production and Fatty Acid Enhancement in the Waterflea,Ceriodaphnia quadrangula,by Using Combination of Light Regime and Food

Combined effects of different light regimes, 6L:6D and 12L:12D (hours light : hours dark, L:D) and algal foods of Scenedesmus quadricauda (S) and Chlorella vulgaris (C) on ephippia production and fatty acid (FA) profile of Ceriodaphnia quadrangula were investigated. The highest resting egg production, density, and specific growth rate were obtained with 6L:6D+S; followed by 12L:12D+S treatment. The C16:0 varied from 16.2 to 22.16 mg/g dry weight (d.w.); C18:1n?9 from 11.03 to 14.94 mg/g d.w; C18:2n?6 from 9.79 to 20.24 mg/g d.w; and C18:3n?3 from 6.98 to 16.02 mg/g d.w. The amounts of C20:4n?6 (4.36 mg/g d.w) and C20:5n?3 (3.35 mg/g d.w) at 6L:6D+S were highest compared to other treatments. The maximum saturated fatty acids and monounsaturated fatty acids were obtained at 6L:6D+C while maximum polyunsaturated fatty acids observed at 6L:6D+S and 12L:12D+C. The resting egg production and FAs profile could be improved when the frequency of changes from light to dark were increased. Our findings also indicate a significant increase in the quantity of C18:3n?3 in C. quadrangula populations during resting egg formation, hence, implying that manipulation of light regime and algal food can improve performance of C. quadrangula as a live food in aquaculture industries, especially for larval feeding.     

Comparison of Growth and Fatty Acids Composition of Freshwater Rotifer, Brachionus calyciflorus Pallas, Fed with Two Types of Microalgae at Different Concentrations

As algae and their concentrations are important factors for mass culture of rotifer, two experiments were conducted to find the effects of two types of algae, Chlorella sp. and Scenedesmus obliquus, and three concentration of chosen algae (0.1 × 10⁶, 1 × 10⁶, and 10 × 10⁶ cells/mL) on growth and fatty acid composition of freshwater rotifer, Brachionus calyciflorus. The result of the first experiment showed that the maximum density of rotifer was significantly higher when fed with Chlorella sp. (478 individuals/mL) than fed with S. obliquus (328 individuals/mL). Mean population growth rate (r) was 0.61 and 0.44 for rotifer fed with Chlorella sp. and S. obliquus, respectively. The amount of highly unsaturated fatty acid (HUFA) in rotifer fed with Chlorella sp. (3.32%) was relatively more than those fed with S. obliquus (2.65%). Then, Chlorella sp. was selected based on better performance. In the second experiment, the maximum rotifer density of 108 ± 8, 489 ± 47, and 493 ± 51 individuals/mL was reached after 5 d for the respective Chlorella sp. concentrations; at concentration of 10 × 10⁶ cells/mL, the maximum density of 1820 ± 47 individuals/mL was obtained. Mean growth rate at mentioned concentrations was 0.18, 0.42, and 0.51/d, respectively. Increase in algal concentration was associated with a relative increase in HUFA and decrease in monounsaturated fatty acid.     

A comparative histopathological, immunohistochemical and nested-PCR study for diagnosis of infectious pancreatic necrosis in the naturally infected cultured rainbow trout (Oncorhynchus mykiss)

To confirm the diagnosis of the infectious pancreatic necrosis, the pancreas, liver, kidney and spleen specimens from 140 rainbow trout (Oncorhynchus mykiss) of weight ranges from 15 to 250?g were processed for routine histopathological and immunohistochemical (IHC) studies together with a nested-PCR using primers that amplify a 164-bp product. Of the 140 fish samples, 37 (26.4%) had a final diagnosis of IPN on the basis of hematoxylin and eosin staining (H&E), while 39/45 (86.6%) were positive by IHC method. With the nested-PCR, 59/140 (42.1%) fish samples were positive. The IHC and nested-PCR showed higher prevalence than histopathology (P?<?0.05). Based on the nested-PCR, as the fish weight increased, IPN positive results decreased (P?<?0.05). However, IHC method detected IPNV constantly in these weight ranges. Only IPNV serotype Sp was identified by nucleotide sequencing and immunohistochemistry, and antiserum to IPNV serotype Ab and IHNV showed negative results in IHC. This is the first comparative diagnostic study of IPN at different weight ranges in cultured salmonids.     

Opposite effects of two organic wastes on the physical quality of an agricultural soil

Soil application of organic wastes (OWs) can be beneficial for soil quality, depending on the quality of the wastes as well as on the amended soil. We performed a field experiment comparing the effects of two different OWs, an industrial sewage sludge (ISS) and a municipal solid waste compost (MSWC), on the physical, chemical and biological quality of an agricultural soil cultivated with maize in central Iran. The two OWs were mixed into the topsoil of the plots at rates of 15 and 45 t ha^?1 (dry matter). The analysis of soil samples taken 31, 74, 132 and 241 days after OW application showed both OW increased organic matter, microbial respiration, and urease activity and decreased bulk density. In contrast, they had opposite effects on water retention and saturated hydraulic conductivity. While the MSWC increased water retention at high saturation and saturated hydraulic conductivity, the ISS decreased them. The negative effects of the ISS on physical soil quality, which may have been due to pore-clogging and hydrophobicity effects, were related to a smaller yield increase in the ISS than in the MSWC treatments, demonstrating the importance that physical OW properties can have for the quality of amended soil.     

Improvement of reproductive indices,lysozyme activity,and disease resistance in live‐bearing ornamental fish,Poecilia latipinna using Artemia supplementation with treated yeast cell,Saccharomyces cerevisiae

In the present study, the effects of Artemia supplemented with 2‐β‐mercapto‐ethanol (β‐ME) treated yeast cell, Saccharomyces cerevisiae, on growth and reproductive performance, lysozyme activity, and disease resistance to Aeromonas hydrophila of freshwater ornamental species, Poecilia latipinna, were investigated. Within 60 days, molly fish were fed with three treatments including commercial food (T1), un‐supplemented Artemia (T2), and Artemia supplemented with β‐ME‐treated yeast cell (at concentration of 4 × 10⁷ CFU/L of water) (T3). After the feeding period, the fish were exposed to 100 μl of a suspension (1.1 × 10⁷ cells/ml) of A. hydrophila (BCCM5/LMG3279) and the cumulative mortality rates were recorded for 12 days. No significant difference was found between survival rate and growth performance of P. latipinna except for weight gain that was higher in fish fed through Artemia supplemented with β‐ME‐treated yeast cell compared to control group. Fecundity rate was significantly improved in fish fed using T3 with the maximum amount of 49.5 ± 2.29 per female (p < 0.05). Besides, lysozyme activity was significantly increased in group 3 (p < 0.05). Moreover, lowest fish mortality was significantly observed in this treatment (p < 0.05). In addition, the number of colonies formed by yeast cell in T3 (634 × 10³ CFU/g intestine) showed significant difference with other treatments (p < 0.05). In sum, Artemia enriched with β‐ME‐treated yeast improved reproductive indices, immune responses, and resistance against A. hydrophila of P. latipinna.     

Compensatory growth,plasma hormones and metabolites in juvenile Siberian sturgeon (Acipenser baerii,Brandt 1869) subjected to fasting and re‐feeding

A 7‐week study was conducted to investigate the effect of different fasting and re‐feeding regimes on compensatory growth and some physiological parameters of juvenile Siberian sturgeon (Acipenser baerii). Fish (46.5 ± 0.5 g) were fed on a diet (containing 450 g/kg crude protein and 20 MJ/kg digestible energy) according to four feeding regimes in triplicate including: control group (C, fed everyday), W1 (2 weeks of feeding followed by 1 week of fasting and 4 weeks of re‐feeding), W2 (1 week of feeding followed by 2 weeks of fasting and 4 weeks of re‐feeding) and W3 (3 weeks of fasting followed by 4 weeks of re‐feeding). The fasted groups including W1 (119.6 ± 2.1 g), W2 (118.0 ± 1.7 g) and W3 (108.5 ± 4.8) significantly lost their weights during fasting phase and did not attain the final weight of the C (137.3 ± 1.7 g) after re‐feeding phase. The re‐feeding phase increased the specific growth rate in the fasted groups compared to the C (p < .05). After the fasting phase, concentrations of T₃, T₄, glucose, total protein and triglyceride in plasma of fasted groups were decreased, but levels of total cholesterol, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase increased compared to the C. After re‐feeding phase, except for glucose level, all mentioned metabolites were restored in the plasma of W1 group, but total protein level and aspartate aminotransferase concentrations in plasma were not restored in W2 and W3 groups. Overall, our finding demonstrated 4 weeks of re‐feeding was too short to induce full compensatory growth in A. baerii juveniles.     

Schwannoma of the External Auditory Canal in a Filly: A Case Report

Schwannomas of the external auditory canal (EAC) are exceedingly rare in human beings and domestic animals. Herein we describe the clinicopathological and immunohistochemical features of a benign schwannoma arising in the EAC of a 2.5-year-old filly. Microscopically, the mass showed a spindle cell tumor composed of hypocellular Antoni type B areas as a myxomatous arrangement of mesenchymal cells and hypercellular Antoni type A areas displaying short fascicles of densely packed neoplastic cells in the collagenous stroma. Immunohistochemically, the tumor cells were diffusely positive for S100 protein and vimentin but negative for Ki67. It was concluded that schwannomas should be included in the differential diagnosis of EAC masses, and immunohistochemical markers such as S100 protein can strongly help in differentiating this tumor from other spindle cell tumors.